In pressing process, a topmost plate member is separated from laminated plate members to be supplied to a press forming machine. It is general to separate the plate members by lifting the topmost plate member by a suction pad. However, the laminated plate members are coated with an oil lubricant having a high viscosity, a rust preventing oil, or the like and are brought into close contact with each other by their own weight. Therefore, it is difficult to completely separate the plate members by such a method and there is a case of simultaneously lifting up a plurality of sheets of plate members. When the plurality of sheets of plate members are taken, the plurality of sheets of plate members are simultaneously supplied to the press forming machine and destroying a die is a concern.
Hence, a method of separating plate members as shown by FIG. 14 is adopted. According to the method, there are used a plurality of pieces of air cylinders 50 each attached with a suction pad 51 at a front end of an output rod 50a. First, the suction pads 51 are arranged substantially in a lattice shape to be adsorbed onto a surface of a laminated topmost plate member W. Next, while pressing the topmost plate member W by the suction pad 51 on a center side of the plate member W, the topmost plate member W is lifted by the remaining suction pad 51. Then, both side edges of the topmost plate member W are rolled up. In the drawing, the air cylinder 50 to be contracted is painted in gray color. Finally, the topmost plate member W is separated by lifting the suction pad 51 on the center side. A method similar thereto is described in Patent Reference 1.
Further, in order to completely separate the plate member W, there is a case of also using the following method. That is, an oil film between the plate members W is removed by lifting the suction pad 51 while blowing air to a gap between the plate members W from a pipe 52. Further, by engaging an end edge of the lifted plate member W by an exfoliating member 53, the plate member W is elastically deformed to promote to separate the plate member W.
Further, there is also proposed a method of forming a gap between plate members by laminating the plate members provided with recesses and projections and lifting the topmost plate member by a suction pad while blowing air from the gap (Patent Reference 2).
Patent Reference 1: JP-A-06-263275
Patent Reference 2: JP-A-04-39225